1. Field of the Invention
The present invention relates to an endoscope-image processing apparatus for performing image processing, which emphasizes an endoscope image which is detected in a visible region, on the basis of a signal of pigment concentration distribution which is calculated by pigment-amount calculation means, to produce the endoscope image, which is provided with ordinary characteristics of the endoscope image and characteristics of the pigment concentration distribution.
2. Description of the Related Art
In recent years, an endoscope in which medical treatment, can be performed without excision by the fact that a body cavity of a patient is observed and a treatment tool is used as occasion demands has widely been used in a medical field.
Further, there is a case where image processing is performed with respect to an endoscope image which is produced by an endoscope, whereby image processing is applied to facilitate discrimination of a normal part or a lesion part.
Regarding the endoscope image, as a prior art which discloses image processing, there is known a method in which RGB images are converted into hue, saturation and brightness and, thereafter, emphasis processing is performed, as disclosed in Japanese Patent Laid-Open No. SHO 62-266028. A method in which histograms of respective hue, saturation and brightness are elongated and are moved, is disclosed in Japanese Patent Laid-Open No. SHO 63-54144. A method in which a quantity of hemoglobin is calculated to perform imaging, is disclosed in Japanese Patent Publication No. HEI 5-3295.
Moreover, as disclosed in Japanese Patent Laid-Open No. HEI 2-224635, processing in which a difference between images which are separated in color from each other is taken to perform emphasis processing on the basis of information thereof is performed.
However, the processing method disclosed in each of Japanese Patent Laid-Open No. SHO 62-266028 and Japanese Patent Laid-Open No. SHO 63-54144 aims at emphasis processing which is matched to a visual sense of a human being. Accordingly, in a case, for example, where color emphasis is performed, a change of delicate color is emphasized. Therefore, contrast is too strong, and an image is inadequate to perform observation for a long period of time.
Furthermore, in the method in which the quantity of hemoglobin is imaged as disclosed in Japanese Patent Publication No. HEI 5-3295, comparison with an endoscope image which is detected in an ordinary or normal visible region is required. That is, the image is brought to an image in a two-dimensional pattern in which an outline and a stereoscopic structure of an affected or diseased part are unknown. Accordingly, by comparison with an ordinary endoscope image, it becomes necessary and indispensable to perform confirmation of a position and a shape or contour of the affected part or the like. In this case, there is such a drawback that, if both the images cannot simultaneously be displayed, confirmation of the position and the contour becomes difficult.
Meanwhile, in the processing method disclosed in Japanese Patent Laid-Open No. HEI 2-224635, the possibility of producing an image which is provided with organism functional information and characteristics of the ordinary endoscope image cannot be totally denied. However, it becomes very difficult to produce an image which is provided with characteristics suitable for diagnosis.
That is, in the publication, the image emphasis performs multiplication between the color signal and the difference signal substantially in proportion to the quantity of hemoglobin, for example. Accordingly, there are many cases where the characteristics of the normal endoscope image are largely varied or modified by the quantity of hemoglobin. Thus, it is possible to change color of the affected part so as to be conspicuous, for example. However, since the healthy parts are also changed in tone, it becomes difficult to notice an affected part. Thus, the image is not provided with characteristics suitable for diagnosis.
Generally, an image in which it is easy to detect the early stages of a lesion (hereinafter referred to as "an early stage of a lesion") is provided with characteristics slightly different from a condition of a healthy part (hereinafter referred to as "a healthy part") becomes an image which is provided with characteristics suitable for diagnosis. In this case, in order to easily identify the early stages of a lesion, it is desirable that the healthy part is also provided with characteristics which are not substantially changed with the tone of the normal endoscope image.
That is, an image processing unit in which image processing capable of assuring the production of an image which is provided with a tone of a normal endoscope image with respect to most parts and which is provided with characteristics which are conspicuous in deceased lesion parts is performed is adequate for diagnosis.
For this reason, it becomes necessary to improve upon the prior art disclosed in the above-described publications so as to ensure production of the image which is provided with the characteristics of both the images and which is suitable for diagnosis.